The present invention relates broadly to an assembly for joining threaded pipes and other tubular sections, and more particularly to such an assembly which is adapted for use with a pressure-venting gasket.
In basic construction, gaskets of the type herein involved are formed of a relatively compressible, annular seal member having a central aperture configured for registration with the corresponding margins of a pair of mating surfaces. The seal member is supported by an annular metal or plastic retainer which may be machined, stamped, molded or otherwise formed to conform to the surface geometry of the mating surfaces. Particularly, the seal member may be molded-in-place or mounted in a groove formed into one or both sides of the retainer, or about the inner and/or outer periphery of the retainer to form an integral gasket structure. Representative such gaskets are shown, for example, in U.S. Pat. Nos. 3,195,906; 3,215,442; 3,259,404; 3,578,346; 3,635,480; 3,720,420; 3,746,348; 4,026,565, 4,625,978, and are marketed commercially by the O-Seal Division of Parker-Hannifin Corporation, San Diego, Calif., under the tradenames xe2x80x9cGask-O-Sealxe2x80x9d and xe2x80x9cIntegral Seal.xe2x80x9d
Retainer gaskets of the type herein involved are employed in a variety of sealing applications, such as in commercial, industrial, or military equipment, vehicles, or aircraft for compression between the opposing or faying surfaces of a pair of mating parts or structures to provide a fluid-tight interface sealing thereof. In service, the gasket is clamped between the mating surfaces to effect the compression and deformation of the seal member and to develop a fluid-tight interface with each of those surfaces. The compressive force may be developed using a circumferentially spaced-apart arrangement of bolts or other fastening members, or by a threaded engagement of the mating parts.
Particularly for oil and gas well drilling assemblies such as described in U.S. Pat. Nos. 4,846,507 and 5,015,017, as well as for other applications involving the sealing of casings, tubing, pipes, lines, or other tubular members connected by means of a threaded pipe joint or other coupling, there exists a need to relieve internal hydrostatic fluid pressure which may be developed as a result of threading compound or other fluid being trapped between the threads of the coupling and the tubular members being joined. In this regard, damage to the gasket and/or the to the joint may result if the pressure which is developed is not relieved from the joint as the parts are being threadably engaged.
In view of the foregoing, it is believed that improvements in retainer gaskets for oil and gas well drilling and other applications would be well-received by the industries concerned. A preferred gasket construction would be economical to manufacture, but also would exhibit reliable sealing performance. Such a gasket additionally would allow for the venting of internally-developed fluid pressure.
The present invention is directed to a retainer gasket construction particularly adapted for venting hydrostatic pressure between a pair of mating interface surfaces which pressure is developed from a source of fluid trapped as one or both of the surfaces are displaced to compress the gasket in forming a fluid-tight seal therebetween. The mating interfacing surfaces may be, particularly, an end face of an internally or externally-threaded pipe, shaft, or tubing, or other tubular member, and a shoulder, ledge, land, or other confronting surface of a matingly-threaded coupling which may be used for joining the tubular member to another such member. The gasket of the invention may be interposed and compressed between the interface surfaces to provide a fluid-tight seal therebetween.
The fluid source may be joint compound which is commonly applied as a lubricant and/or sealant to the threads of the member and/or coupling. As the member and coupling are screwed together, the compound is extruded from the enmeshing threads and may become trapped between the mating interface surfaces. Thereupon, the compound may be compressed as the interface surfaces progress towards one another. If the compound is allowed to remain in the joint being formed, a hydrostatic fluid pressure may be developed having the potential to hydraulically damage the gasket and/or introduce significant stress into the mating parts reducing xe2x80x9cin-servicexe2x80x9d joint efficiency. The gasket of this invention is provided with a venting feature which allows for the relief of the developing fluid pressure, but which, advantageously, does not interfere with the sealing function of the gasket and avoids introduction of hydraulic stresses in the connection beyond those normally developed during assembly.
The gasket herein involved is generally of a closed geometric shape and includes a generally planar, preferably metal, retainer and one or more seal elements supported on at least one and, typically, both sides of the retainer. Advantageously, the retainer delimits the compression of the seal elements to avoid an avoid-compressed condition, and also provides for a direct load path between the interface surfaces to accommodate the development of high bearing stresses with a minimum of torque loss.
The seal elements each may be molded of an elastomeric material in an associated groove formed into a corresponding one of the sides of the retainer. Each of the seal elements may be formed as having a bead or other configuration which is abuttingly contactible in a free state with a corresponding one of the interfaces surfaces, and which is compressible axially thereby into an energized state effecting a fluid-tight seal between the interface surface and the facing side of the gasket. One or more channels are formed through side of the retainer to couple an unfilled void volume formed between each of the compressed seal elements and the corresponding interface surface into fluid communication with an internal or external environment for the venting of the entrapped joint compound or other fluid from the void volume.
To facilitate the installation of the gasket between the interface surfaces, the gasket further may be formed as having a generally annular elastomeric locating member supported circumferentially about the inner or outer perimeter of the retainer. With such member being molded or otherwise attached to the outer perimeter of the retainer, the gasket may be coaxially mounted and retained within, for example, an internal gland of the coupling to be shipped therewith to the job site.
The present invention, accordingly, comprises the apparatus possessing the construction, combination of elements, and arrangement of parts and steps which are exemplified in the detailed disclosure to follow. Advantages of the present invention include a sealing gasket construction which is adapted to vent entrapped fluid but which also exhibits reliable sealing properties and torque retention with a minimum of compression set. Additional advantages include a gasket construction which may be adapted for use with various sealing assembly configurations, and particularly which may be configured to be mounted internally within a coupling for a threaded connection with a pipe, shaft, or tubing end such as for oil and gas well drilling applications. Further advantages include a gasket construction which is economical to manufacture, and which may be made self-locating, retaining, and aligning to simplify and expedite installation. These and other advantages will be readily apparent to those skilled in the art based upon the disclosure contained herein.